Personality and mood characteristics were studied in epileptic patients before and after unilateral left or right temporal lobe resection or intracarotid amytal injection. Physiologic events (skin conductance) and EEG were also monitored during evocative procedures. The research examined the role of the left and temporal lobes in emotional perception and expression, and how brain injury alters these functions. Skin conductance responsivity was recorded from patients following unilateral left or right temporal lobectomy, and normal subjects. Right temporal lobectomy (RTL) patients showed rapid habituation and extinction whereas left temporal lobectomy (LTL) patients showed increased arousal and hypervigilance. In a behavioral paradigm, RTL patients were more responsive to failure than LTL patients. LTL patients demonstrated anxiety, fearfulness and avoidant features; RTL patients presented a dramatic more emotional style. This was confirmed with intracarotid amytal where euphoria followed right and dysphoria followed left injections.